Solemnity

Solemnity, refers to the quality of being solemn, deeply somber or serious, or ceremonies to be performed with such qualities. The word derives from the Latin sollemnis (ritual; festive, solemn, customary, celebrated at a fixed date), itself from sollus (entire). A Solemnity of the Roman Catholic Church is a principal holy day in the liturgical calendar, usually commemorating an event in the life of Jesus, his mother Mary, or other important saints.

A judge can't have any preferred outcome in any particular case. And a judge certainly doesn't have a client. The judge's only obligation — and it's a solemn obligation — is to the rule of law, and what that means is that in every single case, the judge has to do what the law requires.

Samuel Alito, in Confirmation Hearing on the Nomination of Samuel A. Alito, Jr. to be an Associate Justice of the Supreme Court of the United States (January 2006), p. 56

Being solemn has almost nothing to do with being serious, but on the other hand, you can't go on being adolescent forever, unless you are in the performing arts, and anyhow most people can't tell the difference. In fact, though Americans talk a great deal about the virtue of being serious, they generally prefer people who are solemn over people who are serious.
In politics, the rare candidate who is serious, like Adlai Stevenson, is easily overwhelmed by one who is solemn, like General Eisenhower. This is probably because it is hard for most people to recognize seriousness, which is rare, especially in politics, but comfortable to endorse solemnity, which is as commonplace as jogging.
Jogging is solemn. Poker is serious. Once you grasp that distinction, you are on your way to enlightenment.

Russell Baker, in "Why Being Serious Is Hard" in So This Is Depravity (1980), p. 17

In the last analysis ability is commonly found to consist mainly in a high degree of solemnity. Perhaps, however, this impressive quality is rightly appraised; it is no easy task to be solemn.

If you are different, you had better hide it, and pretend to be solemn and wooden-headed. Until you make your fortune. For most wooden-headed people worship money; and, really, I do not see what else they can do.

Everything is theoretically impossible, until it is done. One could write a history of science in reverse by assembling the solemn pronouncements of highest authority about what could not be done and could never happen.

There must be something solemn, serious, and tender about any attitude which we denominate religious. If glad, it must not grin or snicker; if sad, it must not scream or curse. It is precisely as being solemn experiences that I wish to interest you in religious experiences.

There is no absurdity so palpable but that it may be firmly planted in the human head if you only begin to inculcate it before the age of five, by constantly repeating it with an air of great solemnity.

Arthur Schopenhauer, in Studies in Pessimism : A Series of Essays as translated by T. Bailey Saunders (1891), p. 78